Invariants that involve types (stack type of a variable against its IType,
the element type of an array access, the operand types of a comparison)
need a type system to resolve them against, and the only correct one is the
type system the instruction tree was decoded with. Until now CheckInvariant
took only the phase, so such a check had no compilation to use:
DeconstructInstruction.CheckInvariant called IsAssignment with a null type
system, which only held up because the targets it sees are ldloc, whose
InferType never touches the compilation; a ldflda-wrapped or pointer target
would have failed inside the invariant instead of reporting a violation.
Every call site already has that type system in scope: the ILReader's
compilation, the ILTransformContext of the running transform, or the
decompiler's own IDecompilerTypeSystem. It is now passed explicitly and the
base implementation asserts it is present, so a future invariant can rely
on it without re-plumbing the callers.
Assisted-by: Claude:claude-fable-5:Claude Code
This was due to StackType.O doing double-duty as `object` and `other`.
While ExpressionBuilder would often improve the type of such locals, the `object` nevertheless ended up used in a couple of places, e.g. via the `typeHint`. This could result in value types being boxed even though the original IL didn't contain any `box` instruction.
This is an attempt to use better types for stack slot variables created by ILReader. The idea is: there aren't many IL instructions that produce "other" value types, and `InferType()` already handles pretty much all of them, so we can use that to assign types to our stack slots.
It's a bit more tricky if the stack is pushed to on multiple branches that join together before the value is used: here the variable type must be suitable for both assignments. In this case, we go back to the previously-used stacktype.
A call to a value-type constructor is rewritten into
"stobj(target, newobj ...)" because "Struct.ctor(target, ...)" has no C#
equivalent. The rewrite keyed on TypeKind.Struct, so a struct from a
missing assembly resolved as TypeKind.Unknown, fell through to the
ordinary call path and produced a stack-type mismatch.
Metadata cannot settle the question: a TypeRef parent carries no valuetype
bit. The receiver can, though - a constructor invoked with "call" on an
address is a shape only a value type has - so the unresolved case follows
the receiver's stack type and steps aside where metadata does say the type
is a reference type. Reading the receiver has to leave it on the stack for
PrepareArguments, hence the depth-indexed peek.
Assisted-by: Claude:claude-opus-5:Claude Code
Add TaskType.UnpackAnyTask and use it in ILReader.Init / ReadIL so methodReturnStackType and function.AsyncReturnType agree for runtime-async methods that return ValueTask/ValueTask<T> or any [AsyncMethodBuilder]-attributed custom task type. Previously only Task/Task<T> were unpacked, leaving AsyncReturnType=void while the IL Leave value carried the unpacked element type, which tripped the StackType assert in ExpressionBuilder.Translate.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Detect MethodImplOptions.Async (0x2000) in ILReader and unpack Task/Task<T>
return types so the IL Leave value and function.AsyncReturnType match the
source signature. Add CSharp15_0 (Preview also bumped to 1500) and a
RuntimeAsync setting (default on, gated to >=CSharp15_0), expose it in the
Languages dropdown, mask the synthetic MethodImplAsync bit out of the
decompiled [MethodImpl], and add a .runtimeasync test suffix.
This way we avoid having to extract later, as we will never inline if the `isinst` argument if this could result in it being unrepresentable in C#.
This commit also refactors inlining restrictions to avoid requiring special cases in ILInlining itself.
But when making this change, I discovered that this broke our pattern-matching tests, and that the weird IL with double `isinst` is indeed generated by the C# compiler for `if (genericParam is StringComparison.Ordinal)` style code. So instead we also allow `isinst` with a `box(expr-without-side-effects)` argument to be represented with the `expr is T ? (T)expr : null` emulation.
This makes our logic more similar to that used by the dotnet runtime. This lets us infer correct stack types in edge cases such as #2401. It also improves support for obfuscated control flow such as #2878.
This is a performance optimization: we dramatically reduce the amount of ILVariables created;
and thus need to spend less time in the first ILInlining run.
or implicit sequence point without creating overlapping sequence points.
If such a location cannot be found do, nothing. Fill in the
gaps with hidden sequence points.
Also emit a sequence point for
the prolog to account for seqeunce point there emitted by the C#
compiler. Without this, the debugger can stop there on a step in
using the original pdb, then decompile resulting in a no-code at this
location failure.
Unreachable code is not part of the dominator tree, which most of our transforms are based on.
In particular, dominance-based loop detection runs into the problem where unreachable code might have jumps into two independent loops. In that case, it's impossible to place the unreachable code in a way that avoids assertions / generating invalid C#.
We establish the invariant that all blocks in a BlockContainer must be statically reachable from the entry point (-> every block is part of the dominator tree). This means transforms no longer have to deal with special cases for unreachable code.
The "Remove dead and side effect free code" option still has an effect on dead stores, but unreachable code is now always removed (previously this also was dependent on this option).
Siegfried Pammer
Daniel Grunwald
ElektroKill
dotnet format
Jackson Davis
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